TORONTO, ON -- March 5, 1999 -- In a newly-published study of approximately 900 smokers, Glaxo Wellcome’s non-nicotine, prescription medicine Zyban(R) (bupropion hydrochloride) Sustained-Release Tablets was shown to be nearly twice as effective as a nicotine patch in helping smokers quit and stay smoke free for up to one year.

The study released yesterday in the New England Journal of Medicine is the first study to evaluate the efficacy of Zyban relative to other smoking cessation therapies and to examine the safety of the medication when used in combination with nicotine replacement therapy (Novartis’ Habitrol(R)).

An earlier study, which compared several different doses of Zyban to placebo, was published in 1997 in the New England Journal of Medicine. The results of this earlier study showed that treatment with Zyban was significantly more effective than placebo in helping people quit smoking.

"Until recently, the nicotine patch was considered the first-line intervention for smoking cessation. In this study, the abstinence rates yielded by bupropion were consistently superior," said Douglas Jorenby, Ph.D., assistant professor at the University of Wisconsin Medical School and the lead author of this study. "These findings indicate that bupropion should be viewed as first-line therapy for smoking cessation."

In addition to producing significantly higher long-term abstinence rates than those produced by the patch, this study also showed that Zyban reduced withdrawal symptoms during the treatment period. Withdrawal symptoms included craving for cigarettes, restlessness, increased appetite, depressed mood, anxiety, difficulty concentrating, irritability/frustration/anger and disrupted sleep.

Zyban offers smokers a unique quitting process. Smokers continue to smoke for up to two weeks after starting on Zyban so that blood levels are maximised. This may help smokers ease into their quit date and maximise their chances of quitting.

"The results show that Zyban helps reduce the urge to smoke and helps make quitting bearable both short and long term," said Michael Fiore, M.D., M.P.H., director of the Center for Tobacco Research and Intervention at the University of Wisconsin Medical School and a professor in the department of medicine. "The fact that we now have this information showing that Zyban can increase the likelihood of quitting is a message that I hope will encourage more and more people who are thinking about quitting smoking to make that effort and get this incredible health risk out of their lives."

Dr. Andrew Pipe of the University of Ottawa Heart Institute, and one of Canada's leading smoking cessation experts, echoes Dr. Fiore's sentiments.

"As a physician who sees and treats people who are addicted to nicotine, I am encouraged by these results which should give renewed hope to the more than three million Canadians who are preparing to quit smoking."

Dr. Pipe added that because smoking remains the leading cause of preventable death, few other measures could benefit the health of Canadians and the health care system as much as reducing smoking.

The double-blind, placebo-controlled trial compared treatment with Zyban 300 mg/day (taken as 150 mg twice a day), a nicotine patch (Habitrol(R)), combination of Zyban and the patch and placebo. The study involved 893 chronic smokers who smoked at least 15 cigarettes a day and who were randomised to one of the four treatments for nine weeks. All patients received brief individual smoking-cessation counselling. Patients were evaluated weekly during the nine-week treatment phase and then followed-up at weeks 10, 12, 26 and 52. Abstinence was confirmed if patients self-reported they had not smoked in the previous seven days. This was verified biologically by measuring exhaled carbon monoxide.

At the one-year follow-up examination, the cessation rates were 15.6, 16.4, 30.3 and 35.5 per cent for the patients receiving placebo, nicotine patch, Zyban, and the combination of Zyban and the patch, respectively. Zyban and combined therapy had significantly higher quit rates than the patch throughout the study. Combined therapy had the highest quit rates throughout the study but these results were not significantly different from Zyban alone. Quit rates in clinical trials are influenced by the population selected and may be lower in unselected populations.

Active treatment also had an effect on withdrawal symptoms, one of the major obstacles that smokers face when they try to quit. Patients in the active treatment groups experienced fewer withdrawal symptoms than patients taking placebo. This suppression of withdrawal symptoms persisted, in general, throughout the treatment period.

The most common adverse events seen in the study for Zyban alone or in combination with the patch that exceeded placebo were insomnia (42 percent and 48 percent respectively versus 20 percent for placebo and 30 percent for the patch alone) and dry mouth (11 percent and nine percent respectively versus four percent for both placebo and for the patch alone). The most common adverse events in the study for the patch versus placebo were dream abnormalities (18 percent) site reactions (19 percent) and insomnia (30 percent).

There were no seizures reported in this study. However, the use of Zyban is associated with a dose-dependent risk of seizure. Therefore, higher than recommended doses should not be prescribed and Zyban should not be used in people who are already taking Wellbutrin(R) SR or any medications containing bupropion. Zyban should also not be used in patients with a seizure disorder or who have a history of or are currently diagnosed with bulimia or anorexia nervosa. It also should not be used in people who are taking or have recently taken a monoamine oxidase inhibitor (MAOI).

Zyban is the first nicotine-free prescription medicine available as an aid to quitting smoking and was cleared for use by Canada’s Health Protection Branch in July 1998.

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